Various techniques will be used to distinguish between the viral nucleotide sequences specified by different endogenous murine leukemia viruses in the DNA of rodents with differing expression of MLV information. Studies on the nondefective Ad2-SV40 hybrid viruses will emphasize the kinetics of transcription of specific SV40 mRNAs, in vitro protein synthesis of early SV40 proteins, transformation, and the effects of specific SV40 insertions and Ad2 deletions on transcription. Studies on Adenovirus 2 will emphasize in vitro transcription, in vivo synthesis of structural proteins, and the kinetics of viral maturation. The "enhancement" phenomenon will also be explored, regarding the transcription and translation of Ad2 RNA in the presence and absence of SV40 products. Studies on SV40 will be concerned with the genesis of "early" RNA with regard to the configuration of SV40 DNA. The relation of specific areas and nucleotide sequences of the EBV genome to specific biological activities of this virus will be explored, as will the association of EBV DNA with host DNA in a variety of cells. We shall initiate a quantitative evaluation of laminar air-flow rooms and prophylactic antibiotics in the treatment of lymphomas and leukemias which resist conventional chemotherapy, and in human bone marrow transplantation.